Thursday, April 19, 2012

Popper on science as falsification

It's worth going back and reading this now and again. Popper may not have the entire truth about how science is separate from non-science, but he scores some good points. I always love the little story about Adler:

As for Adler, I was much impressed by a personal experience. Once, in 1919, I reported to him a case which to me did not seem particularly Adlerian, but which he found no difficulty in analyzing in terms of his theory of inferiority feelings, Although he had not even seen the child. Slightly shocked, I asked him how he could be so sure. "Because of my thousandfold experience," he replied; whereupon I could not help saying: "And with this new case, I suppose, your experience has become thousand-and-one-fold."

What I had in mind was that his previous observations may not have been much sounder than this new one; that each in its turn had been interpreted in the light of "previous experience," and at the same time counted as additional confirmation. What, I asked myself, did it confirm? No more than that a case could be interpreted in the light of a theory. But this meant very little, I reflected, since every conceivable case could be interpreted in the light Adler's theory, or equally of Freud's. I may illustrate this by two very different examples of human behavior: that of a man who pushes a child into the water with the intention of drowning it; and that of a man who sacrifices his life in an attempt to save the child. Each of these two cases can be explained with equal ease in Freudian and Adlerian terms. According to Freud the first man suffered from repression (say, of some component of his Oedipus complex), while the second man had achieved sublimation. According to Adler the first man suffered from feelings of inferiority (producing perhaps the need to prove to himself that he dared to commit some crime), and so did the second man (whose need was to prove to himself that he dared to rescue the child). I could not think of any human behavior which could not be interpreted in terms of either theory. It was precisely this fact—that they always fitted, that they were always confirmed—which in the eyes of their admirers constituted the strongest argument in favor of these theories. It began to dawn on me that this apparent strength was in fact their weakness.

Well, one problem is that we all use hypothetico-deductive reasoning in everyday life. And it is used by scholars in the humanities who are not usually regarded as scientists.

I've written a few pieces here and there about what I think was new with the rise of science back in the 16th and (especially) 17th centuries, epitomised by the approach of Galileo. A greatly increased emphasis on hypothetico-deductive reasoning was certainly one of those things, and is doubtless a distinguishing feature. Others included the greater/more sophisticated use of mathematics, and the use of new instruments such as the telescope and the microscope to extend the human senses. All of these created synergies with each other.

But as you know, I think the sciences and humanities are continuous, with no clear dividing line between them. Also, Popper was not trying to demark science from the humanities, and he might even have thought it a false distinction, but from a kind of intuitive (if elaborate) pre-science which may sometimes have grains of truth but is in danger of being pseudo-science.

Still, the expression "non-science" is ambiguous, and I think it's worth keeping this in mind.

I think it would be more precise to talk about the novel use of careful quantitative measurements as a basis on which to build and test a (mathematical) theory. I think this is a key feature distinguishing science from non-science, rather then simply the use of sophisticated mathematics. From Pythagorian mysticism to dubious financial wizardry, we see clearly that to have a precise mathematical model of something is not good enough -- one needs to base that model on measurements, and to keep it "minimal", so too speak: it should only serve to explain the raw data and predict more of it, not to make the theory look nicer (although somehow a correct and explanatory mathematical model tends indeed to be esthetically pleasing).

(I know Galileo is famous for saying that the Book of Nature appears to be written in the language of mathematics, but the Pythagorians believed the same yet were not considered as being scientific - unless one counts their achievements in pure maths and perhaps the harmonic law of vibrating strings, which might well be the first mathematical law of physics ever formulated.)